n6 THE THEORY OF MUTATION 



of quite recent date, and their recognition is largely 

 due to the exertions of Bateson. But the idea that 

 this is the way in which evolution takes place is very 

 ancient, as a few quotations will clearly demonstrate. 



The idea that definite structures may arise, each as a 

 whole and in a perfect condition, was clearly propounded 

 by Aristotle in a passage which it is a little curious to 

 find quoted at the beginning of the ' Origin of Species.' 

 Darwin's note is to the following effect : After re- 

 marking that rain does not fall in order to make the 

 corn grow, any more than it falls to spoil the farmer's 

 corn when threshed out of doors, Aristotle adds, ' So 

 what hinders the different parts of the body from 

 having this merely accidental relation in nature ? as 

 the teeth, for example, grow by necessity the front 

 ones sharp, adapted for dividing, and the grinders 

 flat, and serviceable for masticating the food ; since 

 they were not made for the sake of this, but it was the 

 result of accident. And in like manner as to the other 

 parts in which there appears to exist an adaptation 

 to an end. Wheresoever, therefore, all things together 

 that is, all the parts of one whole happened like 

 as if they were made for the sake of something, these 

 were preserved, having been appropriately constituted 

 by an internal spontaneity ; and whatsoever things 

 were not thus constituted, perished and still perish.' 



Upon the above passage from Aristotle Darwin 

 comments as follows : ' We here see the principle of 

 natural selection shadowed forth, but how little 

 Aristotle fully comprehended the principle is shown 

 by his remarks on the formation of the teeth.' We 



